Plot 4

Two player game

Rules

Two players alternate in placing balls of either color on a 7x6 board. Not
exactly placing, because the balls have gravity and fall down to the
lowest unoccupied square on the column. The goal is to get as many
4-in-a-row's as possible. A 5-in-a-row counts as two, 6 as 3, and 7 as 4.